How to show name of course in INNER JOIN?
inner join 3 tables
inner join with where clause
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inner join on multiple columns
I have two tables:
courses. Inside users table i have filed
course where i have course id. Inside courses table i have just
I need to get popular course. I do request:
SELECT u.course, COUNT(*) as freq FROM users u INNER JOIN courses c ON u.course = c.id GROUP BY u.course
As a result: id => freq. But i need to replace ID to NAME of course. How?
You don't say what database you use, but I would assume you can use CTEs since most modern databases do. Your query can be written as:
with x as ( select course, count(*) as freq from users group by course ), y as ( select max(freq) as max_freq from x ) select c.name, x.freq from x join y on x.freq = y.max_freq join courses c on c.id = x.course
This query has the [desirable?] side effect that it shows more than one course, if there are more than one tied in first place.
c.name to both the
SELECT clause and the
GROUP BY clause.
SELECT u.course, c.name, COUNT(*) as freq FROM users u INNER JOIN courses c ON u.course = c.id GROUP BY u.course, c.name;
SQL Inner Join to Two or More Tables, The SQL INNER JOIN is the relation database workhorse. Use it to To be clear, it is best practice to prefix the columns with the table name. The same Other than the tables being the same, you see there is nothing remarkable about this type of join. Kris has written hundreds of blog articles and many online courses. INNER JOIN. The inner JOIN is used to return rows from both tables that satisfy the given condition. Suppose , you want to get list of members who have rented movies together with titles of movies rented by them. You can simply use an INNER JOIN for that, which returns rows from both tables that satisfy with given conditions.
SELECT u.course, COUNT(*) as freq, c.name FROM users u INNER JOIN courses c ON u.course = c.id GROUP BY u.course
Microsoft Office 2013: Illustrated, Third Course, Learning Outcomes • Create a left join • Define left and right joins STEpS join lines in Query Design View if the linking fields have the same name and data type all records from the Courses table because the default join type, the inner join, Students has id, name columns Courses has also course.id, course.name and there is third table joining the Students and Courses table. Registration : stu_id, course_id One Student can take one or many courses. I would like to find the name of Students registered in only one course.
If your DBMS supports
row_number this will be suitable:
select t.id, c.name, t.cnt from course c join ( select c.id, count(1) cnt, ROW_NUMBER() over(order by count(1) desc) rn from users u join course c on c.id = u.course group by id )t on t.id = c.id and t.rn = 1
How to Make a Join Easier to Read using Table Aliases, Table Aliases are a way to create a shortened table name for use in SQL. It is part of my Join Together Now course. In the top you can see an INNER JOIN that we've worked on in the past, where we specified the join using only table The SQL INNER JOIN clause tells the database to only return rows where there is a match found between table1 and table2. An INNER JOIN is most often (but not always) created between the primary key column of one table and the foreign key column of another table.
SQL: JOIN on tables | Computer programming, Inner joins don't include non-matching rows; whereas, outer joins do include 2 tables with a join so that you can see each person's name next to their hobby. Note: We can also write JOIN instead of INNER JOIN. JOIN is same as INNER JOIN. Example Queries(INNER JOIN) This query will show the names and age of students enrolled in different courses. SELECT StudentCourse.COURSE_ID, Student.NAME, Student.AGE FROM Student INNER JOIN StudentCourse ON Student.ROLL_NO = StudentCourse.ROLL_NO; Output:
How to write a SQL statement in SQL Server to display student name , How to write a SQL statement in SQL Server to display student name, course, and grade INNER JOIN TABLEENTRIES ON EA7MARKINGCOLUMNS. SELECT department_name AS 'Department Name', COUNT(*) AS 'No of Employees' FROM departments INNER JOIN employees ON employees.department_id = departments.department_id GROUP BY departments.department_id, department_name ORDER BY department_name; Sample Output:
SQL joins and how to use them, Different joins available in SQL are explained -- inner, left, right, and cross joins. type of join to use; The name of the second table to join; The join condition. other ones we've looked at so far and so we won't show an example for this. subqueries here as you'll get to work with them some more later in course LS180. The most important and frequently used of the joins is the INNER JOIN.They are also referred to as an EQUIJOIN.. The INNER JOIN creates a new result table by combining column values of two tables (table1 and table2) based upon the join-predicate.
- Popular course is the course which have most rows in
userstable where field
courseis id of course.
c.nameto the select?
- It seems like there should be a third table establishing a many-to-may relationship between users and courses.
- Can u add some expected data and expected result set?
- @IdontDownVote I believe that's actually more standard SQL behavior and something MySQL has made an exception to for a while. The reason it's not generally supported is that the value of the non-aggregated column is ambiguous within the group. In some cases that doesn't matter, though.
- it wont work since
select course, count(*) as freq from usersneeds
- @YuriyTsarkov Good catch! Fixed.
- @HarshaB select course if from users, count rows and named as freq and course name from course table. Then i need to INNER JOIN course table where i want to find course id equal in user table field course id
- The comment was the part of review quality of answer. I was not looking for your answer, just checking the quality of answer. You can edit your answer and can add the explanation.
- I didn't downvote, but you should include some explanation with the code to make the answer more useful.